Filter
Top Products
5.2.4 Digital I/O Register
5.2.4.1 Digital Output
The four digital output lines share the same pins on the interface connector as the four
external channel selection bits. When using an expansion card(s), bit 5 of the control register
(base + 2) should be set to “1” so that the four digital output lines will be driven by the
external channel selection bits from the scan FIFO. If bit 5 of the control register is set to
“0”(default after reset), then the four output lines are driven by the values in bits 0 to 3 latched
during the last write operation. In other words, the digital output bits are valid only when the
DAQP card is NOT in expansion mode. Table 5-14 lists the digital output register bit
definition.
Table 5-14. Digital Output Register Bit Definition
Ignored
Reserved as all “0”
4-7
IgnoredIgnored, the four output lines will
be driven by the external channel selection
bits in the scan list FIFO
Digital output bits 0-30-3
Expansion ModeNormal ModeBits
5.2.4.2 Digital Input
Two of the digital input lines are shared with the external trigger (bit 0) and the external clock
(bit 2). The other two lines are used for external gain control in expansion mode (if bit 2 of the
control register is set to “1”). The digital input lines are not latched.
Although the digital input lines are also used as external trigger, external clock and the
external gain selection; the current status of these lines will always be returned when reading
the port. The line status does not affect the digital output register. It’s contents cannot be read
back directly, even though they share the same port offset with the digital input register. Table
5-15 lists the digital input register bit definition.
Table 5-15. Digital Input Register Bit Definition
All “0”
All “0”
4-7
External gain select, high bit
Digital input bit 3
3
The same as in normal modeDigital input bit 2, also serve as external clock2
External gain select, low bit
Digital input bit 1
1
The same as in normal mode
Digital input bit 0, also serve as external trigger
0
Expansion ModeNormal ModeBits
DAQP-208/208H/308 Users Manual 49